An important problem in data analysis for pattern recognition and signal processing is finding a suitable representation. For historical and computational simplicity reasons, linear models that optimally encode particular statistical properties of the data have been desirable. In particular, the linear, appearance-based face recognition method known as “Eigenfaces” is based on the principal component analysis (“PCA”) technique of facial image ensembles. See L. Sirovich et al., “Low dimensional procedure for the characterization of human faces,” Journal of the Optical Society of America A., 4:519-524, 1987, and M. A. Turk and A. P. Pentland, “Face recognition using eigenfaces,” Proceedings IEEE Computer Society Conference on Computer Vision and Pattern Recognition, pp. 586-590, Hawaii, 1991, both of which are hereby incorporated by this reference. The PCA technique encodes pairwise relationships between pixels, the second-order statistics, correlational structure of the training image ensemble, but it ignores all higher-order pixel relationships, the higher-order statistical dependencies. In contrast, a generalization of the PCA technique known as independent component analysis (“ICA”) technique learns a set of statistically independent components by analyzing the higher-order dependencies in the training data in addition to the correlations. See A. Hyvarinen et al., Independent Component Analysis, Wiley, New York, 2001, which is hereby incorporated by this reference. However, the ICA technique does not distinguish between higher-order statistics that rise from different factors inherent to an image formation—factors pertaining to scene structure, illumination and imaging.
The ICA technique has been employed in face recognition and, like the PCA technique, it works best when person identity is the only factor that is permitted to vary. See M. S. Bartlett, “Face Image Analysis by Unsupervised Learning,” Kluwer Academic, Boston, 2001, and M. S. Bartlett et al., “Face recognition by independent component analysis,” IEEE Transactions on Neural Networks, 13(6):1450-1464, 2002, both of which are hereby incorporated by this reference. If additional factors, such as illumination, viewpoint, and expression can modify facial images, recognition rates may decrease dramatically. The problem is addressed by multilinear analysis, but the specific recognition algorithm proposed in M. A. O. Vasilescu et al. “Multilinear analysis for facial image recognition,” In Proc. Int. Conf on Pattern Recognition, Quebec City, August 2002 was based on linear algebra, and such algorithm does not fully exploit the multilinear approach.